The invention relates to magnetic resonance (MR) tomography. This produces a pictorial representation of partial regions from the interior of a test object using coils for applying magnetic primary and gradient fields to the test object and an antenna for picking up the deflection of the nuclear spins of the test object from their equilibrium position by radio-frequency magnetic excitation pulses.
A device of this kind is described in U.S. Pat. No. 3,564,398. This device is suitable for deflecting the hydrogen atom nuclei of the test object and to detect their swinging back into equilibrium. Based on the measured signals, the proton distribution of a certain stratum of the test object can be represented pictorially.
In a device of this kind the problem arises that for the observation of moving body regions a triggering (or gating) of the imaging process must occur as a function of the respiration and/or the heartbeat (EKG) of the patient. To this end a respiration detector and EKG electrodes may be provided which generate electrical signals depending on the respiration and on the cardiac activity, which signals cause the gating of the imaging process.
One object of the invention is to develop a device of the initially mentioned kind so that there are formed disturbance-free physiological test signals, which in particular depend on respiration and on the EKG, and which permit a satisfactory gating of the imaging process.